1. Field of the Invention
The present invention relates to new uses of synergistic fungicidal combinations of 2-(thiocyanomethylthio)benzothiazole (TCMTB) and a thiophanate compound to control fungal growth on a variety of substrates and in aqueous systems.
2. Description of the Related Art
Fungi, also referred to as molds, rusts, mildews, smuts, etc., are multicellular organisms that are typified by a branching cellular structure. Fungi develop from microscopic spores, which are omnipresent in nature (in soil, water and air), to macroscopic structures that grow on almost any substance which offers a source of moisture and some form of nutrients.
Because fungi are widely present throughout the environment, they are also found in various industrial operations where they can cause economic damage resulting from their growth on industrial raw materials and goods. Fungal growth can cause deterioration, i.e., discoloration or actual degradation of the material or good, thereby reducing its economic value.
An example of an industry where fungal growth may dramatically reduce the value of the end product is the leather industry. Different species of fungi, such as molds, are encountered at various stages in the processing of leather. For instance, the pickling stage, wherein the hides are transformed into an acid environment for tanning, even strong pickle solutions are subject to attack by some microorganisms. Fungi, molds in particular, may be troublesome and cause discoloration of the pickled stock, especially if the stock is held for a period of time before tanning, Finally, the moisture, pH, and temperature characteristics of the tanning process create almost ideal conditions for the growth of a variety of fungi, including Aspergillus, Penicillium and Paecilomyces, which may discolor and permanently downgrade the economic value of finished leather.
Other industries where fungal growth is also a problem include: the lumber industry: mold growth on wooden substrates, so-called sapstaining and decay of untreated lumber, particle board and other wooden products; the papermaking industry: fungal growth on cellulose pulp; fungal slime in paper mill systems; the textile industry: mold growth and its resulting staining and decay of textile fabrics; the agricultural industry: mold and other fungal growth on seeds, plants, and crops; and the coating industry: fungal attack on glues and surface coatings. Common fungal species that grow on these types of materials include Aspergillus, Penicillium and Paecilomyces.
In addition to solid substrates, aqueous systems containing organic materials are also subject to microbiological attack and degradation. Microorganisms may grow, for example, in aqueous systems such as latexes, metal working fluids, cooling water, aqueous emulsions, aqueous detergents, and resins formulated in aqueous solutions, emulsions, or suspensions. Such products frequently contain relatively large amounts of water. The temperature at which these products are stored as well as their pH makes these products susceptible to the growth of fungi.
Fungal degradation of such aqueous systems containing organic material may manifest itself in a variety of problems, including loss of viscosity, gas formation, objectionable odors, decreased pH, emulsion breaking, color change, and gelling. Additionally, fungal deterioration of aqueous systems can also cause fouling of the related water-handling system, which may include cooling towers, pumps, heat exchangers, and pipelines, heating systems, scrubbing systems, and other similar systems.
Various chemicals, generally known as industrial fungicides, have been used to prevent this fungal deterioration of industrial and raw materials and goods. For instance, 2-(Thiocyanomethylthio)benzothiazole (TCMTB) is one effective industrial fungitide. The use of TCMTB as an industrial fungicide has been described in U.S. Pat. Nos. 4,293,559, 4,866,081, 4,595,691, 4,944,892, 4,839,373, and 4,479,961. TCMTB is manufactured by Buckman Laboratories International, Inc., and sold as Busan.RTM. 30WB, Busan.RTM. 1030, Busan.RTM. 1118 and other products.
Another example of an industrial fungicide is thiophanatemethyl (TPM). TPM is also known as 4,4'-o-phenylenebis[3-thioallophanate], as dimethyl [(1,2-phenylene) bis(iminocarbonothioyl)]biscarbamate, and cerocobin-m. TPM is used as a fungicid.RTM. in agricultural applications, such as seed treatment to protect against fungal growth on the seeds. TPM is manufactured by Nippon Soda Co., Ltd., Japan, and sold as the product Topsin-M.
Despite the existence of such fungicides, there remains a need for cost-effective technology that performs in a particular system and offers equal or better protection at lower cost and lower concentrations of fungicide. When used, the concentration of fungicides and the corresponding treatment costs for such use, can be relatively high. Important factors in the search for cost-effective fungicides include efficacy in the particular industrial application, the duration of fungicidal effect, the ease of use, and the effectiveness of the fungicide per unit weight.